Hi

I´ve a question concerning the rust protection coating on the underside of the car. After 14 years respectively 14 very hard winters the black stuff needs to be renewed. Of course I refreshed it every two years but on some places it ist getting more and more cracked up and will soon not be able to protect the underside of the car from rust. So I´ve decided that it has to be removed completely also to gain access to metal plates from the outside. From the inside, when you lift the carpets, the floor plates look like in 1989 - no bullshit it´s perfectly true I swear!!!! I never had problems with water resting on the floor or stuff like this! Nevertheless there are some rust pickles visible from the outside on the black stuff underneath the car - they must come from somewhere so the black stuff has to go.

Now my question: What is the best way to remove all the black protective coating, what tools will be needed for that type of work and finally what is the best way to make it rustproof for long time - and lots of hard winters - again?

Thanks for any advice :-)

Ciao

M.P.

When I repaired the rust out on the entire driver's side of a 245 recently, nothing worked as fast of as well at removing the undercoating as using a propane torch flame to bubble up the coating, then using a putty knife to scrape off the thick stuff.

I followed up with Eastwood Company's Undercoating Remover spray to get the residue.

Curiously, that product smells exactly like oven cleaner. Hmmmm.

Others have said they had good results using a twisted wire cup on the end of their electric drill.

Point is, there's no magic chemical that's going to do better than mechanical means.

When under my 89 245 last night for some OD solenoid work, I noticed that the undercoating is cracked all the way across the driver's-side floorboard in-line with the rear of the driver's seat. The crack is large enough that I could pick pieces of rusted metal out with a screwdriver. I can also see it flex when pushing down from the inside.

Am now wondering what it would feel like to fall through the floor while doing 70 mph on a California freeway.

I would be interested in any advice you have on effecting repairs.

I have only owned this vehicle for 4 months and there are no signs of underbody rust so I am assuming this was primarily caused by interior water. Carpet looks fine but I haven't pulled it yet.

Ed
89 245

Ed,

You have the interior water lleak-caused rust out on the floor panel that is common to this series of car.

You must pull up your carpet to appreciate the extent of the problem.

Most likely the rust has eliminated the seam where the "Bench" the driver's chairs sits on is welded to the floorboard. It's not cause for throwing away the car, but at least consider if you want to weld or fasten in some sort of support panel.

Likely thing is, you'll need to replace the rot under the chair "trestle" (this bench or trestle is a single panel which spans the width of the car, rocker to rocker and inclues the "hump" over the transmission. The floor panel, which is rotted, is a separate panel under the trestle.)

It gets difficult to repair the rust when it is between the trestle and the floor. I think there might also be a frame brace under the car at this place. So, it's hard to just go under the car and slice out the rotted floor.

On one car I did, I resorted to just "sending in" some rust fighting liquid, neutralizing that, then "sending in" some rust preventative paint before topcoating. (Believe I used Eastwood's Corroless) By "sending in" I mean I tied a small paintbrush onto the end of a thin stick and slathered the area best I could. Used forced air -- shop vac, compressed, and/or space heater -- to dry things before painting)

The rear foot rest area is likely damaged, too. This is the easier place to repair. It is a flatter panel (with "U" channels formed into it for strength). Because I neded to remove and replace the entire area, I went with a flat panel (no "U" channels) which I cut from the side of my old washing machine!)

The third problem area is the first 6 inches inboard from the rocker panel seam (a flange pointing down toward the ground which contains about four 3/4" openings as water drains).

Sometimes the rust runs the length of this area about 1-2" inboard of the seam between the rocker and the floorboard.

Volvo actually makes a replacement panel, ($50) running wheel to wheel about 6" wide, complete with the "U" channel bends to match up with the floors.

Most important thing, though, find out what the water is getting in and seal that.

Then assess your rust repair needs.

Do a search of the archived posts for "floor repair" or similar. About a year ago someone posted his pictures of this same job. Very instructive.

Write me again if you need more help.

Why on earth would you want to remove it completely?

I live in Ottawa and let me tell you this stuff lasts way more than 13 or 14 years... OK I do agree that it tends to flake off once rust develops between it and the metal, but that can be fixed.

Also, I forsee more damage in taking it off, if you start scratching the sheet metal you will likely open areas for new corrosion to form. The sheet metal is specially coated to avoid entry of moisture.

Mine is an 89 and I too have a few (but very minor) spots where it has peeled off. THOSE AREAS ONLY, I would peel off all lose coating and even further but only with a plastic scraper, and then re-apply new undercoating. Once that is done there is no reason for further rust to form.

So no rust on floor huh? Interesting, I was going to pull up my carpet tonight and take a peak, after my posting earlier today. Haven't done it yet. My car shows no rust underneath, and it has not really ever had water spills inside. Thanks! You have given me confidence to delay this work!

Not sure where you are located, but after years of experience and a lifetime of living in salted roads and six months of snow the ABSOLUTE BEST product I've ever seen is RUSTCHECK. This is a reddish oil based product that comes out somewhat foamy, then within seconds turns really thin and continues to "creap" around the metal and corners and crevices for days afterwards. These characteristics give it a thumbs up, especially for coating inside of door panels and behinds fenders and around body moldings... Hell I even spray it (can) around the window rubber molding and it creps into there within days. No metal is untouched by RUSTCHECK. Naturally, I would not use this as an undercoating. It is thin and the rain and road elements, and snow would just wear it out from under the car. The undercoating needs to be thick and durable, like that black stuff the factory put under our tanks.

Good luck, enjoy the car, they say at 13 years old it has just entered puberty.

ciao,
Greg Mustang
Ottawa-Montreal
Canada

Hi

First of all thanks very much for the detailled answer :-)

I know it sounds ridiculous to remove the whole stuff underneath the car but I would simply do an overall job at this stage. I´ve done the method you described several times and was quite pleased with the results but nontheless I would prefer to clean it up completely to put all new coatings of rustproofing under the car. Perhaps the whole job is not necessery - or I have too much time left :-) - but I would simply assure myself that the whole underbody is completely rust free!

By the way - my motoring area is the "mountain belt" of Croatia along the adriatic ocean! The winters are very hard and sometimes last over 5 months too, so the car really needs to be protected against rust :-)

After 14 years of owning this specific car - since three years it is my own property (that´s when my father gave my this "heirloom of our family")
I could only support the opinion that it has just enterd puberty!

Again - thanks a lot and I´ll post my advances of this work as soon as I come along with it :-)

Ciao

M.P.

well not exactly sure on how to to remove it all.But when i was draing ing my gas tank the gas did very good job of taking it off the tank with no rubbing lol.
Good Luck.
--
Dan D. '85 245 DL , '93 945 .Delanisdjd@aol.com

...good to know :-)

cu

M.P.

You can try a few things like Dan's gas (stinks), paint thinner (stinks, too), turpentine (pine scented maybe), let it soak in and scrape off with putty knives and screwdrivers, better wood and plactic (lexan) wedges. Be careful of fires, have a hose near by. Got a light? Nasty job at best.

Check with the undercoating experts and body shops first.

Let us know what you used and how you fared. I have to do the same on a '70 not a Volvo.
--
Tom F